Bear Robotics Software Engineer interview questions

Medium level coding interview for 12 hours, unproctored. there are multiple choice questions as well, but they are not tech related. Then they called me for one more, it will happen in few days.

Was a Hackerearth OA before moving to an on-site whiteboard. Was told in person that there were 4 technical rounds in total so 2 more if I cleared the on-site, for a startup it seems pretty long-winded and unnecessary. On-site interview was average, the interviewer didn't seem experienced and was passive-aggressive in poking holes in my CV explanation. There was a whiteboard question after that but the interviewer did not really communicate and was silent through the entire planning and coding. it was a one-sided communication with me relaying my thought process and writing code on my end. The interview experience would have been more interesting if the interviewer was genuinely engaged but it was disappointing as he mentioned that he wanted another way of answer even though both the method which I solved it in has the same time complexity, they didn't have the courtesy to even send a rejection email. Expects candidate to go on site and prepare but can't send even a rejection email after weeks.